Dynamical Evolution of Gravitational Leptogenesis

TL;DR

This paper investigates how quantum gravitational effects influence lepton number evolution in the early universe, revealing mechanisms that could generate matter-antimatter asymmetry through curvature interactions.

Contribution

It demonstrates that CP even curvature interactions break lepton number conservation and affect lepton density evolution, extending previous models focused on CP odd effects.

Findings

Potentially significant gravitationally-induced lepton-antilepton asymmetry at early times

Curvature interactions modify lepton number dynamics in expanding universe

Generalized Boltzmann equation captures these effects

Abstract

Radiatively-induced gravitational leptogenesis is a potential mechanism to explain the observed matter-antimatter asymmetry of the universe. Gravitational tidal effects at the quantum loop level modify the dynamics of the leptons in curved spacetime and may be encoded in a low-energy effective action Seff. It has been shown in previous work how in a high-scale BSM theory the CP odd curvature-induced interactions in Seff modify the dispersion relations of leptons and antileptons differently in an expanding universe, giving rise to an effective chemical potential and a non-vanishing equilibrium lepton-antilepton asymmetry. In this paper, the CP even curvature interactions are shown to break lepton number current conservation and modify the evolution of the lepton number density as the universe expands. These effects are implemented in a generalised Boltzmann equation and used to trace the dynamical evolution of the lepton number density in different cosmological scenarios. The theory predicts a potentially significant gravitationally-induced lepton-antilepton asymmetry at very early times in the evolution of the universe.